The Rock Cycle-
The rock cycle shows how one type of rocky material
gets transformed into another in response to changing conditions.

Weathering, Erosion, and Transportation

Rocks exposed at Earth’s surface are constantly changed
by the atmosphere, hydrosphere, and biosphere.

Weathering is the group of physical and chemical
processes that change the character of rocks at or near Earth’s surface.
Weathering involves the breakdown of rock and the formation of new minerals.

Erosion is
the physical removal and transportation of rock particles from the
source by water, wind, or ice.

There are two types of
weathering:

Mechanical weathering

-The physical disintegration of rock into smaller pieces.

-Facilitated by the action of ice,
water, and wind.

Chemical weathering

-Chemical decomposition of rock
from exposure to atmospheric gases (oxygen, water vapor and carbon dioxide) or
liquid water (which is often acidic).

-New
minerals form.

-The
rate of chemical weathering
increases as surface area of rock increases.

Weathering and the Earth Systems

Within our solar system, Earth seems to be the only
planet with surface rocks actively being weathered by wind, water, and living
organisms.

Atmosphere-
Gases like O2, CO2,
and H2O are critical to the chemical weathering of rock. These
gases react with pre-existing minerals to produce new minerals that are in equilibrium with surface
conditions.

ex. CO2 + H2O
à H2CO3
(Carbonic Acid)

Chemical weathering
is essential to life in that it removes carbon dioxide from the
atmosphere, reducing green-house effect.

Atmospheric wind
also causes the mechanical breakdown of rock via a sandblasting effect.

Hydrosphere- Oxygen dissolves in water and
then can oxidize iron in rocks:

Feldspars (the most common minerals in
Earth's crust)- Slightly acidic rainwater (H2CO3)
attacks feldspar, producing clay minerals (hydrated sheet silicates).
The K+, Na+,
and Ca2+ ions are released into the water.

Minerals highest on Bowen’s
reaction series are most susceptible to weathering. Therefore, olivine and
pyroxene weather quickly to produce clays and iron oxides.

Quartz is
the least susceptible to
chemical weathering. It can be transported all the way to the oceans.

Soil -
Soil is a layer of weathered, unconsolidated material
on top of bedrock. Common soil constituents include: